LXR linux/drivers/pps/clients/pps-gpio.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * pps-gpio.c -- PPS client driver using GPIO
   4 *
   5 * Copyright (C) 2010 Ricardo Martins <rasm@fe.up.pt>
   6 * Copyright (C) 2011 James Nuss <jamesnuss@nanometrics.ca>
   7 */
   8
   9#define PPS_GPIO_NAME "pps-gpio"
  10#define pr_fmt(fmt) PPS_GPIO_NAME ": " fmt
  11
  12#include <linux/init.h>
  13#include <linux/kernel.h>
  14#include <linux/interrupt.h>
  15#include <linux/module.h>
  16#include <linux/platform_device.h>
  17#include <linux/slab.h>
  18#include <linux/pps_kernel.h>
  19#include <linux/pps-gpio.h>
  20#include <linux/gpio/consumer.h>
  21#include <linux/list.h>
  22#include <linux/of_device.h>
  23#include <linux/of_gpio.h>
  24#include <linux/timer.h>
  25#include <linux/jiffies.h>
  26
  27/* Info for each registered platform device */
  28struct pps_gpio_device_data {
  29        int irq;                        /* IRQ used as PPS source */
  30        struct pps_device *pps;         /* PPS source device */
  31        struct pps_source_info info;    /* PPS source information */
  32        struct gpio_desc *gpio_pin;     /* GPIO port descriptors */
  33        struct gpio_desc *echo_pin;
  34        struct timer_list echo_timer;   /* timer to reset echo active state */
  35        bool assert_falling_edge;
  36        bool capture_clear;
  37        unsigned int echo_active_ms;    /* PPS echo active duration */
  38        unsigned long echo_timeout;     /* timer timeout value in jiffies */
  39};
  40
  41/*
  42 * Report the PPS event
  43 */
  44
  45static irqreturn_t pps_gpio_irq_handler(int irq, void *data)
  46{
  47        const struct pps_gpio_device_data *info;
  48        struct pps_event_time ts;
  49        int rising_edge;
  50
  51        /* Get the time stamp first */
  52        pps_get_ts(&ts);
  53
  54        info = data;
  55
  56        rising_edge = gpiod_get_value(info->gpio_pin);
  57        if ((rising_edge && !info->assert_falling_edge) ||
  58                        (!rising_edge && info->assert_falling_edge))
  59                pps_event(info->pps, &ts, PPS_CAPTUREASSERT, data);
  60        else if (info->capture_clear &&
  61                        ((rising_edge && info->assert_falling_edge) ||
  62                        (!rising_edge && !info->assert_falling_edge)))
  63                pps_event(info->pps, &ts, PPS_CAPTURECLEAR, data);
  64
  65        return IRQ_HANDLED;
  66}
  67
  68/* This function will only be called when an ECHO GPIO is defined */
  69static void pps_gpio_echo(struct pps_device *pps, int event, void *data)
  70{
  71        /* add_timer() needs to write into info->echo_timer */
  72        struct pps_gpio_device_data *info = data;
  73
  74        switch (event) {
  75        case PPS_CAPTUREASSERT:
  76                if (pps->params.mode & PPS_ECHOASSERT)
  77                        gpiod_set_value(info->echo_pin, 1);
  78                break;
  79
  80        case PPS_CAPTURECLEAR:
  81                if (pps->params.mode & PPS_ECHOCLEAR)
  82                        gpiod_set_value(info->echo_pin, 1);
  83                break;
  84        }
  85
  86        /* fire the timer */
  87        if (info->pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) {
  88                info->echo_timer.expires = jiffies + info->echo_timeout;
  89                add_timer(&info->echo_timer);
  90        }
  91}
  92
  93/* Timer callback to reset the echo pin to the inactive state */
  94static void pps_gpio_echo_timer_callback(struct timer_list *t)
  95{
  96        const struct pps_gpio_device_data *info;
  97
  98        info = from_timer(info, t, echo_timer);
  99
 100        gpiod_set_value(info->echo_pin, 0);
 101}
 102
 103static int pps_gpio_setup(struct platform_device *pdev)
 104{
 105        struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
 106        struct device_node *np = pdev->dev.of_node;
 107        int ret;
 108        u32 value;
 109
 110        data->gpio_pin = devm_gpiod_get(&pdev->dev,
 111                NULL,   /* request "gpios" */
 112                GPIOD_IN);
 113        if (IS_ERR(data->gpio_pin)) {
 114                dev_err(&pdev->dev,
 115                        "failed to request PPS GPIO\n");
 116                return PTR_ERR(data->gpio_pin);
 117        }
 118
 119        data->echo_pin = devm_gpiod_get_optional(&pdev->dev,
 120                        "echo",
 121                        GPIOD_OUT_LOW);
 122        if (data->echo_pin) {
 123                if (IS_ERR(data->echo_pin)) {
 124                        dev_err(&pdev->dev, "failed to request ECHO GPIO\n");
 125                        return PTR_ERR(data->echo_pin);
 126                }
 127
 128                ret = of_property_read_u32(np,
 129                        "echo-active-ms",
 130                        &value);
 131                if (ret) {
 132                        dev_err(&pdev->dev,
 133                                "failed to get echo-active-ms from OF\n");
 134                        return ret;
 135                }
 136                data->echo_active_ms = value;
 137                /* sanity check on echo_active_ms */
 138                if (!data->echo_active_ms || data->echo_active_ms > 999) {
 139                        dev_err(&pdev->dev,
 140                                "echo-active-ms: %u - bad value from OF\n",
 141                                data->echo_active_ms);
 142                        return -EINVAL;
 143                }
 144        }
 145
 146        if (of_property_read_bool(np, "assert-falling-edge"))
 147                data->assert_falling_edge = true;
 148        return 0;
 149}
 150
 151static unsigned long
 152get_irqf_trigger_flags(const struct pps_gpio_device_data *data)
 153{
 154        unsigned long flags = data->assert_falling_edge ?
 155                IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
 156
 157        if (data->capture_clear) {
 158                flags |= ((flags & IRQF_TRIGGER_RISING) ?
 159                                IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING);
 160        }
 161
 162        return flags;
 163}
 164
 165static int pps_gpio_probe(struct platform_device *pdev)
 166{
 167        struct pps_gpio_device_data *data;
 168        int ret;
 169        int pps_default_params;
 170        const struct pps_gpio_platform_data *pdata = pdev->dev.platform_data;
 171
 172        /* allocate space for device info */
 173        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 174        if (!data)
 175                return -ENOMEM;
 176        platform_set_drvdata(pdev, data);
 177
 178        /* GPIO setup */
 179        if (pdata) {
 180                data->gpio_pin = pdata->gpio_pin;
 181                data->echo_pin = pdata->echo_pin;
 182
 183                data->assert_falling_edge = pdata->assert_falling_edge;
 184                data->capture_clear = pdata->capture_clear;
 185                data->echo_active_ms = pdata->echo_active_ms;
 186        } else {
 187                ret = pps_gpio_setup(pdev);
 188                if (ret)
 189                        return -EINVAL;
 190        }
 191
 192        /* IRQ setup */
 193        ret = gpiod_to_irq(data->gpio_pin);
 194        if (ret < 0) {
 195                dev_err(&pdev->dev, "failed to map GPIO to IRQ: %d\n", ret);
 196                return -EINVAL;
 197        }
 198        data->irq = ret;
 199
 200        /* initialize PPS specific parts of the bookkeeping data structure. */
 201        data->info.mode = PPS_CAPTUREASSERT | PPS_OFFSETASSERT |
 202                PPS_ECHOASSERT | PPS_CANWAIT | PPS_TSFMT_TSPEC;
 203        if (data->capture_clear)
 204                data->info.mode |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR |
 205                        PPS_ECHOCLEAR;
 206        data->info.owner = THIS_MODULE;
 207        snprintf(data->info.name, PPS_MAX_NAME_LEN - 1, "%s.%d",
 208                 pdev->name, pdev->id);
 209        if (data->echo_pin) {
 210                data->info.echo = pps_gpio_echo;
 211                data->echo_timeout = msecs_to_jiffies(data->echo_active_ms);
 212                timer_setup(&data->echo_timer, pps_gpio_echo_timer_callback, 0);
 213        }
 214
 215        /* register PPS source */
 216        pps_default_params = PPS_CAPTUREASSERT | PPS_OFFSETASSERT;
 217        if (data->capture_clear)
 218                pps_default_params |= PPS_CAPTURECLEAR | PPS_OFFSETCLEAR;
 219        data->pps = pps_register_source(&data->info, pps_default_params);
 220        if (IS_ERR(data->pps)) {
 221                dev_err(&pdev->dev, "failed to register IRQ %d as PPS source\n",
 222                        data->irq);
 223                return PTR_ERR(data->pps);
 224        }
 225
 226        /* register IRQ interrupt handler */
 227        ret = devm_request_irq(&pdev->dev, data->irq, pps_gpio_irq_handler,
 228                        get_irqf_trigger_flags(data), data->info.name, data);
 229        if (ret) {
 230                pps_unregister_source(data->pps);
 231                dev_err(&pdev->dev, "failed to acquire IRQ %d\n", data->irq);
 232                return -EINVAL;
 233        }
 234
 235        dev_info(data->pps->dev, "Registered IRQ %d as PPS source\n",
 236                 data->irq);
 237
 238        return 0;
 239}
 240
 241static int pps_gpio_remove(struct platform_device *pdev)
 242{
 243        struct pps_gpio_device_data *data = platform_get_drvdata(pdev);
 244
 245        pps_unregister_source(data->pps);
 246        if (data->echo_pin) {
 247                del_timer_sync(&data->echo_timer);
 248                /* reset echo pin in any case */
 249                gpiod_set_value(data->echo_pin, 0);
 250        }
 251        dev_info(&pdev->dev, "removed IRQ %d as PPS source\n", data->irq);
 252        return 0;
 253}
 254
 255static const struct of_device_id pps_gpio_dt_ids[] = {
 256        { .compatible = "pps-gpio", },
 257        { /* sentinel */ }
 258};
 259MODULE_DEVICE_TABLE(of, pps_gpio_dt_ids);
 260
 261static struct platform_driver pps_gpio_driver = {
 262        .probe          = pps_gpio_probe,
 263        .remove         = pps_gpio_remove,
 264        .driver         = {
 265                .name   = PPS_GPIO_NAME,
 266                .of_match_table = pps_gpio_dt_ids,
 267        },
 268};
 269
 270module_platform_driver(pps_gpio_driver);
 271MODULE_AUTHOR("Ricardo Martins <rasm@fe.up.pt>");
 272MODULE_AUTHOR("James Nuss <jamesnuss@nanometrics.ca>");
 273MODULE_DESCRIPTION("Use GPIO pin as PPS source");
 274MODULE_LICENSE("GPL");
 275MODULE_VERSION("1.2.0");
 276